1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a liquid crystal display panel and a fabricating method thereof that are capable of forming an insulating film exposing a metal pattern without a photolithography process.
2. Description of the Related Art
In general, a liquid crystal display (LCD) controls the light transmittance of liquid crystal cells using electric field, to thereby display a picture on a liquid crystal display panel. To this end, the LCD includes a liquid crystal display panel having liquid crystal cells arranged in an active matrix form, and driving circuits for driving the liquid crystal panel. The liquid crystal display panel is provided with pixel electrodes and a reference electrode, i.e. common electrode, to supply the electric field to each one of the liquid crystal cells. Usually, the pixel electrode is assigned to each one of the liquid crystal cells on a lower substrate, while the common electrode is formed as an integrated whole on the entire surface of an upper substrate. Each pixel electrode is connected to a thin film transistor (TFT) that is used as a switching element. The pixel electrode together with the common electrode drives the liquid crystal cell in response to data signals supplied via the TFT.
As shown in FIG. 1, a liquid crystal display panel in accordance with a related art includes upper and lower array substrates 10 and 20 combined together, and a liquid crystal material 8 between the upper and the lower array substrates 10 and 20.
The liquid crystal molecules of material 8 rotates, in response to the supplied electric field, to thereby regulate the transmittance of incident light via the lower array substrate 20.
The upper array substrate 10 includes a color filter 4 and a common electrode 6 formed on a rear surface of the upper substrate 1. The color filter 4, where red (R), green (G), and blue (B) colored filter layers are arranged in a stripe fashion, makes it possible to display colors by selectively passing light having specific wavelengths. A black matrix 2 is placed between the adjacent colored filters 4, and prevents the degradation of the contrast ratio by absorbing the light incident from the adjacent cells.
The lower array substrate 20 includes: a data line 18 and gate line 12 which cross each other and are insulated by a gate insulating layer formed on the entire surface of the lower substrate 21; and a TFT 16 placed on the crossing of the data and gate lines. The TFT 16 includes: a gate electrode connected to the gate line 12; a source electrode connected to the data line 18; and a drain electrode facing with the source electrode with a channel portion including an active layer and an ohmic contact layer therebetween. The TFT 16 is connected to the pixel electrode 14 via a contact hole passing through a passivation film. In response to gate signals from the gate line 12, the TFT 16 selectively supplies data signals from the data line 18 to the pixel electrode 14.
The pixel electrode 14 is made from a transparent conductive material having a high light transmittance, and is placed on a cell region defined by the data line 18 and gate line 12. An electric potential difference is generated between the pixel electrode 14 and the common electrodes 6 by data signals supplied via the drain electrode. Under the influence of this electric potential difference, the liquid crystal cell residing between the upper and lower substrates 1 and 21 rotates due to the dielectric anisotropy thereof. As a result, the light supplied via the pixel electrode 14 from the light source passes toward the upper substrate 1.
Depending on the circumstances, insulating film 30 including at least one of the gate insulating film and the passsivation film formed on the related art liquid crystal display panel exposes a metal pattern 32 located at its lower portion as shown in FIG. 2. For instance, the passivation film exposes the drain electrode in order to contact the drain electrode with the pixel electrode of the thin film transistor.
In order to expose the metal pattern 32, a photo-resist is coated on the substrate 21 provided with the insulating film 30 and then is by a photolithography employing an exposing process and a developing process using a mask, to thereby form a photo-resist pattern. The insulating film 30 is etched using the photo-resist as a mask so that the metal pattern 32 is exposed.
Because the photolithography process using the mask is required for exposing the metal pattern 32 located at the lower portion of the insulating film 30, the process is complicated and, as a result there is a problem that production cost is increased.